Effects of Tip Clearance on Flow Fields in Transonic Centrifugal Compressors with Low Reynolds Number and Low Specific Speed

Abstract

The objective of the present study is to investigate the effects of the tip clearance on internal flows in transonic centrifugal compressors with low Reynolds number and low specific speed. In order to examine the flow fields inside the centrifugal impellers, steady state single passage RANS calculations are performed. To investigate the effects of the tip clearance on the internal flows, the flow fields are analyzed in detail using visual data mining. For comparison with lower Reynolds number flow fields, the flow fields with higher Reynolds number of a typical centrifugal compressors are analyzed as well. As a result, for both the higher Reynolds number and the lower Reynolds number, the effect of changes in the tip clearance on the vortical flow fields is found to be small. The effect of changes in the clearance on the total pressure ratio and adiabatic efficiency of the lower Reynolds number is greater than the higher Reynolds number.